18 



BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 



It is readily been that Table I will aid greatly in determining the 

 rot in the tree by means of external characters, and after the class of 

 defecl and the cause have been determined by its use it will be com- 

 paratively easy to select the proper rot column in the table of rot 

 percentages for any one tree species. In this manner the two tables 

 can be used conjunctively in securing a more accurate rot percentage 

 for the stand. 1 Until it is possible to obtain accurate data from a 

 large number of trees of all the species composing the prevalent 



forest types of this 

 region, no table of 

 rot percentages will 

 be presented. 



Since the type 

 lines are sketched on 

 the topographic map 

 on the basis of age 

 class, it will be 

 found advantageous 

 to study and record 

 the rot data upon 

 such a basis. This 

 will make it easier 

 to produce patholog- 

 ical maps of the 

 area by using white 

 prints from the type- 

 sheet tracings of the 

 timber survey maps. 

 In a unit crew 

 consisting of two 

 men (an estimator 

 and a topographer), 

 the estimator can be trained to determine the cause of the dis- 

 ease and the amount and therefore the rot percentage, recording 

 such data accurately for the strip which is being surveyed. Since 

 the estimate sheets have blank spaces for the recording of all disease 

 and other injuries suffered by the stand, as well as for the estimated 

 loss in cull due to each, the only change that a more intensive disease 

 survey will incur will be the additional work done by the topog- 

 rapher. He will be required to indicate upon his map the boundaries 



1 Weir, J. R. Difficult problem of the control of fungus diseases in the forest. In 

 Timberman, v. 14, no. 9, p. 27-29, illus. 1913. 



Weir, J. R. Some problems in conservation with reference to forest hygiene. In Tim- 

 berman, v. 14, no. 11, p. 28-31, illus. 1913. 



Meinecke, E. P. Forest tree diseases common in California and Nevada. Washington, 

 D. C. 1914. These publications may be found useful in the determination of various 

 kinds of defects. 



Fig. IS. — Typical rot of the scaly Pholiota in grand fir. 

 Note the horizontal streaks formed by the yellowish felty 

 mycelium. 



